Chop the graphics into segments that appear on the left and right sides of the screen, as well as centers.
What I mean is, You make tiles that will be layed on top of each other, partially blockig the view of others, creating the illusion of depth. By using segments, you can reduce file and game size. I'll whip up and example, and post the images here.
brb.
So as you can see, you only need to build the view out of tiles that comprise segments of the view; just the parts that change.
From there, you start drawing with the furthest parts in view, and lay image segements overtop of that. You use the Vertical lines as division points. Draw the far center first, then the far left and right, then work your way forwards, overlaying as you go.
Please draw a nicer dungeon hallway than i did. I would draw no more than 5-6 steps in depth; it gets awfully small after that.